1. Field of the Invention
The present invention generally relates to amphibious motor vehicles. More specifically, the invention is an amphibious vehicle that utilizes four, six, or eight independent, hydraulically driven wheels when the wheels are in contact with the ground and a pair of propellers when the vehicle is in water. Further, a single pair of levers controls the speed and direction of the vehicle both on land and in water.
2. Description of the Related Art
A variety of amphibious all-terrain vehicles have been devised in an attempt to allow the user to easily traverse from land to water operation and vice versa quickly and easily. The following patents, which are incorporated herein by reference, generally represent the state of the art.
U.S. Pat. No. 3,664,451 describes a vehicle having front and rear body sections rotatably interconnected along the longitudinal axis of the body sections. An engine is located in the front body section and a drive shaft extends through the coupling between the body sections through the compartment of the rear body section and to a gear box on a rear axle located entirely outside of the compartment of the rear body section. Frame members extend from the rear body section to support the rear axle. A propeller may be connected to a drive shaft extending rearwardly from the gear box on the rear axle.
U.S. Pat. No. 4,744,324 describes an all-terrain vehicle that is adapted to amphibious operation by means of a conversion kit that uses rear axle extensions to mount outer rear wheels and radial paddle elements between the inner and outer rear wheels. Flotation is provided by over-size tires.
U.S. Pat. No. 6,672,916 describes an amphibious vehicle having an open seating arrangement and which comprises a drive motor for reciprocally or simultaneously driving an all-wheel drive traveling mechanism and a swimming drive that is configured as a jet drive by means of at least two clutches that operate independently of one another, whereby the drive motor is arranged underneath the seating arrangement in an essentially central manner between the axles of the traveling mechanism.
U.S. Pat. No. 3,444,837 discloses a utility vehicle having structural features directed to a self supporting powered chassis comprising a clutch mechanism that functions by the principal use of planetary gear systems. In addition, the wheels are driven by a series chains and sprockets.
U.S. Pat. No. 3,199,486 describes an amphibious vehicle having a body adapted to be armored and having power driven front and rear axles connected with front and rear wheels for travel on land, propeller means for travel on water; and drive means for said front and rear wheels and for said propeller means, said wheels being equipped with oversized, shot-proof low pressure tires, the tires for said power driven front wheels projecting ahead of said body, and said drive means including transmission means selectively operative to drive said front and said rear wheels together, said wheels and said propeller means simultaneously, and said propeller means separately, and said transmission means including a propeller driving transmission portion and a land driving transmission portion operative at a land traveling speed not exceeding the speed of water travel, said propeller driving transmission portion including a horizontal drive shaft and said propeller means including a propeller drive shaft extending perpendicularly to said horizontal drive shaft and being connected thereto and pivotally movable about its own axis and about the axis of said horizontal drive shaft.
U.S. Pat. No. 5,993,273 describes an amphibious all-terrain vehicle having a substantially rectangular body or shell constructed of a lightweight durable metallic material. A combustion gas engine is coupled to a dual hydraulic pump system. Six-independent wheel motors are symmetrically disposed in series, three on each side of the shell and are plumbed in series for ground-based mobility respectively. Each of the wheel motors penetrates the shell beneath the waterline of the vehicle. An auxiliary hydraulic pump may be provided to drive a hydraulic propeller motor, said motor also penetrating the shell beneath the waterline. Separate controls are used to control the wheels and the propeller.
U.S. Pat. No. 6,666,735 discloses an amphibious off-road vehicle drive that utilizes an internal combustion engine drive system and a liquid propulsion jet drive system jointly functional in a single engine case of the off-road vehicle for enabling forward motion of the vehicle. The jet drive system provides a means for engaging and disengaging with the internal combustion engine drive system. An outrigger flotation device engages with the off-road vehicle and is adapted for adjustment between a stored attitude and a deployed attitude. When the vehicle enters deep water, the jet drive may be employed to propel the vehicle, and the flotation gear may be employed to maintain buoyancy.
U.S. Pat. No. 4,664,051 discloses a flotation kit to be used to adapt a conventional three wheel all-terrain vehicle for amphibious use.
U.S. Pat. No. 3,385,255 discloses a track type amphibious vehicle with three drive wheels for carrying an endless track mounted on each side of the vehicle. The drive wheels on each side are mounted on axles that protrude from a sealed box beam mounted underneath the vehicle, and below the vehicle's waterline, and are driven by a single hydraulic motor that delivers power to each wheel through a chain and sprocket system. The chain drive is lubricated by a reservoir of lubricating fluid contained in said box beam. Propulsion in the water is provided by a pair of auxiliary motors that are releasably mounted on the rear end wall of the vehicle and that drive a pair or propellers. When the vehicle is in the water, both the propellers and the wheels are driven simultaneously.
The complexity of designing a vehicle that can operate effectively on all terrain and easily traverse from land operation to water operation and back has lead to a variety of problems that plague known devices. One problem in known devices is that the drive mechanism, or mechanisms, for the wheels passes through the shell of the vehicle beneath the waterline. Thus, as the drive mechanism is stressed through torque applied by the power source and through vibration and impact as the vehicle traverses uneven ground, the seal around the mechanism, or mechanisms, tends to fail, allowing water into the passenger compartment.
A second problem is the use of drive systems that utilize a single motor to drive all of the wheels on a single side of the vehicle through complex, failure-prone mechanical systems such as the chain-and-sprocket drive system disclosed in U.S. Pat. No. 3,385,255.
A third problem is the fact that known vehicles that utilize a water propulsion system in addition to their drive wheels either require a separate set of controls for the ground and water propulsion mechanisms or, when a single set of controls is used, drive the wheels simultaneously with the water propulsion mechanism. The first situation is a problem because it makes it difficult for a single operator to drive the vehicle out of water effectively because this feat generally requires the operator to coordinate the drive systems such that water propulsion system provides sufficient forward force to allow the wheels to engage with the ground forming the bottom of the body of water without slipping. The second situation is a problem because it siphons power from the water propulsion system and because the rotation of the tires in the water creates drag.
A fourth problem is that the utilization of a single hydraulic system to drive wheel motors and a propeller motor can result subjecting the propeller motor to high pressure when the vehicle is operated in wheels only mode. This can result in a significant drop in performance of the vehicle because hydraulic motors suitable for providing the high RPM output necessary to drive a propeller are typically of the case drain design such as the PGM-330 from Parker Hannifin Corporation. If such a case drain type motor is subjected to high pressure and not allowed to rotate, a leakage through the case drain can occur resulting in a significant loss in performance.
A fifth problem is the complexity and cost of building a vehicle with independent hydraulic systems to control both land and water propulsion motors on the left and right sides of the vehicle that can be operated in three distinct modes—land drive only, land and water drive, and water drive only—using single set of controls.